Node Affinity

本节我们将介绍nodeAffinity，我们将把应用跑在特定的m6a.xlarge机型上，Karpenter将保证开出特定的机型来

先把之前的deploy, provisioner, node template删除：

kubectl delete deployment inflate
kubectl delete provisioners.karpenter.sh default
kubectl delete awsnodetemplates.karpenter.k8s.aws default

部署Provisioner和Node Template：

mkdir ~/environment/karpenter
cd ~/environment/karpenter
cat <<EoF> nodeaffinity.yaml
apiVersion: karpenter.sh/v1alpha5
kind: Provisioner
metadata:
  name: default
spec:
  # References cloud provider-specific custom resource, see your cloud provider specific documentation
  providerRef:
    name: default
  ttlSecondsAfterEmpty: 30

  # Labels are arbitrary key-values that are applied to all nodes
  labels:
    eks-immersion-team: my-team

  # Requirements that constrain the parameters of provisioned nodes.
  # These requirements are combined with pod.spec.affinity.nodeAffinity rules.
  # Operators { In, NotIn } are supported to enable including or excluding values
  requirements:
    - key: "karpenter.k8s.aws/instance-category"
      operator: In
      values: ["c", "m", "r"]
    - key: "kubernetes.io/arch"
      operator: In
      values: ["amd64"]
    - key: "karpenter.sh/capacity-type" # If not included, the webhook for the AWS cloud provider will default to on-demand
      operator: In
      values: ["on-demand"]
  limits:
    resources:
      cpu: "10"

---
apiVersion: karpenter.k8s.aws/v1alpha1
kind: AWSNodeTemplate
metadata:
  name: default
spec:
  subnetSelector:
    alpha.eksctl.io/cluster-name: ${CLUSTER_NAME}
  securityGroupSelector:
    aws:eks:cluster-name: ${CLUSTER_NAME}
  tags:
    managed-by: "karpenter"
    intent: "apps"
EoF

kubectl apply -f nodeaffinity.yaml

部署应用，注意它使用了nodeAffinity的requiredDuringSchedulingIgnoredDuringExecution参数，这将保证强制使用该机型：

cd ~/environment/karpenter
cat <<EoF> constraint-deploy.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: inflate
spec:
  replicas: 3
  selector:
    matchLabels:
      app: inflate
  template:
    metadata:
      labels:
        app: inflate
    spec:
      affinity: 
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
              - matchExpressions:
                - key: "node.kubernetes.io/instance-type"
                  operator: "In"
                  values: ["m6a.xlarge"]
      terminationGracePeriodSeconds: 0
      containers:
        - name: inflate
          image: public.ecr.aws/eks-distro/kubernetes/pause:3.7
          resources:
            requests:
              cpu: 1
      nodeSelector:
        eks-immersion-team: my-team
EoF

kubectl apply -f constraint-deploy.yaml

其中node.kubernetes.io/instance-type属于Well Known labels，更多label可参考：

https://karpenter.sh/docs/concepts/scheduling/#well-known-labels

创建出来的3个pod，Karpenter将开出一台m6a.xlarge机器，并部署到上面：

image-20231028103837311